Here is a followup to a few questions that have come up since my GnuCash Budget post.
How much did I spend for this month?
I find the Cash Flow report useful for this question. (Reports->Income & Expense->Cash Flow). You need to customize the report a bit before you get the information you need though. 1st, change the date range to the period of time you're interested in. 2nd, select any additional accounts you want included. By default, the report only includes expenses and asset (cash) accounts. You need to select any liability accounts (like credit cards) that you spend money from.
When you've set up the report, you get Money In and Money Out sections. The Money Out shows you not only how much each budget account spent, but also you can see which expense accounts you spent the money in.
This is a particular subtlety of this budget system that I really like. You don't have to spend budget money from the same account as the expense. Example: I have my own personal budget but I use it to by items in many different expense accounts, e.g., movies, games, food, computers, etc. The report might look like this:
Budget: My budget: 100
Expense: Food 25
Expense: Movies 25
Expense: Computer 50
I do that exact thing all the time. We might buy a particular expense item but choose to take it out of our savings budget for instance.
Did I go over the budget this month?
This one is easy. There is not "this month" or "last month" in this budget system. You can choose to think of your budget that way, but I like to think of it as a continuous budget amount. Budgets increase when you increase them and decrease when you spend from them. For me, my budget increases when I earn income. That might be monthly, bi-weekly, and it may have occasional spikes. (Like we got our tax refund back, so I added the money from that to our budgets).
How much did I spend on food and transportation this month?
Just look at the Cash Flow report and find the category you're interested in. Note that you can look at both the Expense (how much you spend on a certain thing.) and the Budget (how much you used from the budget.) They may be the same or they may be different depending on how you choose to record transactions.
How much was my net-income for the last quarter?
Since the budget balances to 0, it doesn't affect your balance sheet. You can use the standard GnuCash balance sheet and asset reporting to figure out your income etc. One note though, I try to remember that my budget money will need to be spent at some point in the future.
Which area can I spend less and save more?
This one is pretty easy. Just look at your budget accounts in the main GnuCash window. Since you always see the current balance of your budget account, just look at which ones are positive and which ones are approaching zero (or heaven forbid you didn't go negative did you?).
We transfer money between budgets too. Say I built up over a few months a few hundred extra dollars in my Auto:Fuel budget since gas prices have been low. I can decide to make a transfer from that budget to another one that perhaps we had some extra expense from.
Since writing my original post, I've only grown to like this system more and more. Feel free to post more questions/comments and I'll do my best to answer.